Electroplating brightener compositions and process

ABSTRACT

Zinc or cadmium electroplating brightener compositions for addition to alkaline cyanide electroplating baths comprising an aqueous solution of corn syrup or glucose, vanillin, veratraldehyde, sodium lignin sulfonate and sodium bisulfite.

[75] Inventor: John C. Kosmos, Hasbrouck Heights, NJ. [73] Assignee:Sterwin Chemicals, Inc., New York,

[22] Filed: Mar. 28, 1974 [2]] Appl. No.: 455,526

[52] US. Cl 204/50 Y, 204/DIG. 2, 204/55 Y [51] Int. Cl. C23b 5/10, C23b5/46 [58] Field of Search... 204/50 Y, 50 R, 55 Y, 55 R, 204/DIG. 2

[56] References Cited UNITED STATES PATENTS 2,196,588 4/1940 Hull 204/55Y United States Patent 1 3,850,766

Kosmos [4 Nov. 26, 1974 [54] ELECTROPLATING BRIGHTENER 2,233,500 3/194IWestbrook 204/55 Y 7 3,088,884 5/1963 Passal i 204/55 Y COMPOSITIONS ANDPROCESS 3,285,840 11/1966 Lindemann 204/55 R Primary Examiner-G. L.Kaplan Attorney, Agent, or Firm-Elmer J. Lawson; William G. Webb [57]ABSTRACT Zinc or cadmium electroplating brightener compositions foraddition to alkaline cyanide electroplating baths comprising an aqueoussolution of corn syrup or glucose, vanillin, veratraldehyde, sodiumlignin sulfonate and sodium bisulfite.

12 Claims, N0 Drawings ELECTROPLATING BRIGHTENER COMPOSITIONS ANDPROCESS Pat. No. 1,607,870); lignin sulfonic acid and metal saltsthereof including the sodium salt (U.S. Pat. Nos. 2,740,754; 2,872,392and 3,146,178); certain aromatic aldehydes such as anisic aldehyde (U.S.Pat. No. 2,740,754); and various proteins, such as peptone (U.S. Pat.No. 2,799,635) or hydrolyzed meat protein (U.S. Pat. No. 3,751,348).

It has now been surprisingly found that a combination in an aqueousmedium of corn syrup or glucose, vanillin, veratraldehyde and sodiumlignin sulfonate (together with a molar equivalent amount of sodiumbisulfite equal to the molar equivalent amount of vanillin andveratraldehyde which is used to solubilize the vanillin andveratraldehyde through the bisulfite addition compound), when used as anadditive to alkaline cyanide zinc or cadmium plating baths, providesadvantages over the use of the separate brightener ingredients when usedalone.

Thus, although sodium lignin sulfonate does provide a brighteningeffect, the degree of brilliance obtained over a range of low to highcurrent densities is not uniform when the material is used alone. On theother hand, when combined with the other ingredients of the presentinvention, consistently brilliant deposits are obtained at both high andlow current densities, and furthermore the inclusion of the sodiumlignin sulfonate with the other ingredients tends to extend the lifetimeof the'bath over its normal limit. Glucose or corn syrup,

when used alone, provide only a small degree of bright-' ening, and likesodium lignin sulfonate, give inconsistent results over broadrangesofcurrent densities. Vanillin used alone also provides a brighteningeffect, but consistent results are only obtained at high currentdensities, and darkening ofthe deposit is caused at low currentdensities. veratraldehyde alone causes pitting of the deposit at lowcurrent densities, and furthermore the tolerance ofthe bath toimpurities is diminished relative to results obtained with the instantcompositions. As indicated hereinbelow ammonium heptamolybdate, a knownelectroplating brightener, can also be used in conjunction with thecompositions of the present invention. However, this material used alonecauses blistering of the deposit at high current densities and fails todeposit at low densities and thus is useful alone only at intermediatecurrent densities. On the other hand, the novel combination ofingredients used in the practice of the present invention providesconsistently good results, in terms of brightening effect, tolerance toimpurities, extended bath life and adherence, over a broad range ofcurrent densities.

Moreover, the bath additive compositions useful in the practice of thepresent invention can, if desired, be

used in conjunction with other agents known to provide added brillianceto the electrodeposit such as molybdate salts, for example ammoniumheptamolybdate, or with polysulfides in the case of cyanide zinc baths,for example ammonium, sodium or potassium polysulfide, which are used tocombine with metallic impurities in the electroplating bath and therebyserve to prevent impurities from interfering with deposition of the puremetal.

The bath additive compositions provided by the present invention arepreferably prepared in concentrated form, and in use are further dilutedwith water for addition to new or old working electroplating solutionsin amounts to be described hereinafter. The concentrated form containsfrom 1.0 to 4.3 pounds/gallon of sodium lignin sulfonate, about 0.9pound/gallon of veratraldehyde, from 0.1 to 2.2 pounds/gallon ofvanillin, from 1.5 to 4.5 pounds/gallon of corn syrup or glucose, and amolar equivalent amount of sodium bisulfite corresponding to the totalweight of the vanillin and veratraldehyde. Since, as will be describedhereinafter, the additive compositions can be made up in varyingconcentrations ranging from dilute solutions that can be added directlyto the plating bath to more concentrated solutions that require furtherdilution before addition to the plating bath, the compositions can alsobe described in terms of the relative amounts of the separateingredients. Thus, relative to the veratraldehyde present, the operativeamounts of the separate ingredients, expressed in parts by weight, are:

and a molar equivalent amount of sodium bisulfite corresponding to thetotal molar equivalent amount of the vanillin and veratraldehyde.

The compositions can be used in either barrel or still platingprocedures, and when employed in barrel or still plating of cadmium,they may optionally contain, in addition to the ingredients describedabove, from 0.018 to 0.4 pound/gallon of ammonium heptamolybdate (orfrom 0.02 to 0.4 part by weight relative to veratraldehyde) to improvethe brilliance of the deposit. When employed in barrel or still platingof zinc, they may optionally contain, respectively, from 0.018 to 0.4pound/gallon (0.02 to 0.4 part by weight relative to veratraldehyde) orfrom 0.015 to 0.18 pound/gallon (0.017 to 0.2 part by weight relative toveratraldehyde) of ammonium heptamolybdate.

A preferred composition contains from 1.35 to 3.2 pounds/gallon ofsodium lignin sulfonate, 0.9 pound/- gallon of veratraldehyde, from 0.18to 1.35 pounds/gallon of vanillin, from 2.0 to 4.0 pounds/gallon of cornsyrup or glucose, and a molar equivalent amount of sodium bisulfiteequal to the total amount of vanillin and veratraldehyde. When ammoniumheptamolybdate is used to enhance the brilliance of the deposit incadmium barrel or still plating, it is preferred to use from 0.045 to0.27 pound/gallon of the heptamolybdate, and when the heptamolybdate isused in barrel or still plating of zinc, it is preferred to use,respectively, from 0.045 to 0.27 pound/gallon or from 0.018 to 0.18pound/gallon of the heptamolybdate. Expressed in parts by weightrelative to veratraldehyde, the preferred composition contains:

Sodium lignin sulfonate 1.5-3.5 Veratraldehyde 1.0 Vanillin 0.2-1.5 Cornsyrup or glucose 2.2-4.5

and a molar equivalent amount of sodium bisulfite equal to the totalamount of vanillin and veratraldehyde. When ammonium heptamolybdate isused in barrel or still plating of cadmium or in barrel plating of zinc,a preferred amount is from 0.05 to 0.3 part by weight relative to theveratraldehyde, and when it is used in still plating of zinc, apreferred amount is from 0.02 to 0.2 part by weight relative toveratraldehyde.

In use, the concentrates described above are diluted with three parts ofwater and added to the electroplating bath. In the case of new baths, anamount of the sodiluted solution to provide 1-2 percent by volume of thefinal plating solution is used, whereas in the case of old workingbaths, it is sufficient to add one-half percent by volume of the dilutedconcentrate.

The compositions of the invention, when used in barrel plating ofcadmium, give best results at 9-12 volts E.M.F., while in barrel platingof zinc, best results are obtained at 10-15 volts E.M.F. In stillplating of cadmium, a current density of -80 amperes/ft can be used withadvantage, a current density of -40 amperes/ft being preferred. In stillplating of zinc, good results are obtained at current densities of 10-80amperes/ft a preferred range being -50 amperes/ft In all cases, platingis advantageously carried out at temperatures from 70-90F.

Having described the general manner of making and using the invention,the best mode of carrying out the invention is described by thefollowing specific exam' ples.

EXAMPLE 1 Basic Concentrate A concentrate containing the followingingredients:

Sodium lignin sulfonate 1.49 pounds/gal. Verutraldehyde 0.9 pound/gal.Vanillin 0.6 pound/gal. Corn syrup 2.08 pounds/gal. Sodium bisulfite0.84 pound/gal.

is prepared as follows:

A container of adequate size is charged with about 40 percent of thenecessary quantity of water at l40-l50F., and the sodium ligninsulfonate is added with stirring, followed by the corn syrup which ispreviously warmed to about 120F. The vanillin and veratraldehyde areliquified by warming together on a hot water bath, and the liquid meltis added to the main mixture with stirring. The sodium bisulfite is thenadded slowly with stirring, and stirring is continued until all materialis dissolved. Sufficient water is added to give the desired finalvolume, the solution is cooled to below 100F., and then packed withstirring in polyethylene containers.

A. Zinc Barrel or Still Plating Composition The concentrate so-preparedis diluted with three parts of water, and 10 to 20 gallons of thediluted solution are added to 1,000 gallons of a standard zinc cyanidebath containing:

Zinc cyanide 8.0 oz./gal. Sodium cyanide 5,6 oz./gal. Sodium hydroxide8-10 oZ./gal. Sodium polysulfide 0.12 oz./gal.

Cadmium oxide 3.0 oz./gal. Sodium cyanide 10.4-13.4 oz./ga|. Sodiumhydroxide 1.0 oz./gal.

The bath so-prepared, when used in the barrel plating of cadmium at 9-12volts E.M.F. at 90F. for l0-15 minutes gives an even, bright deposit ofabout 0.0002 inch thickness. C. Cadmium Still Plating Composition Theconcentrate described in Example 1 above is diluted with three parts ofwater, and 10-20 gallons of the diluted solution are added to 1,000gallons ofa cadmium still plating solution containing:

Cadmium oxide Sodium cyanide 3.0 o7../gal. 10.4-18.4 ozjgal.

The bath so-prepared, when used in the still plating of cadmium at l0-40amperes/ft at 70-90F. for 5 minutes gives an even, bright deposit ofabout 0.002 inch thickness.

EXAMPLE 2 To the basic concentrate described in Example 1 above is added0.06 pound/gallon (about 4 grams/liter) of ammonium heptamolybdate. Theconcentrate soobtained is diluted with three parts of water, and 10-20gallons of the diluted solution are added, respectively, to 1,000gallons of the solutions described in Examples 18 and 1C above. Thebaths so-obtained in each case when used, respectively, in barrelplating and still plating of cadmium under the conditions described inExamples 1B and 1C, respectively, give deposits similar to thosedescribed in Examples 18 and 1C, respectively, but having improvedbrilliance thereover.

EXAMPLE 3 To the basic concentrate described in Example 1 above is added0.03 pound/gallon (about 2 grams/liter) of ammonium heptamolybdate. Theconcentrate soobtained is diluted with three parts of water, and 10-20gallons of the diluted solution are added to 1,000 gallons of thesolution described in Example 1A above. The bath so-obtained when usedin still plating of zinc under the conditions described in Example 1Agives a deposit similar to that described in Example 1A but havingimproved brilliance thereover.

EXAMPLE 4 To the basic concentrate described in Example 1 is added 0.06pound/gallon (about 4 grams/liter) of ammonium heptamolybdate. Theconcentrate so-obtained is diluted with three parts of water, and -20gallons of the diluted solution are added to 1,000 gallons of thesolution described in Example 1A above. The bath soobtained when used inbarrel plating of zinc under the conditions described in Example 1Agives a deposit similar to that obtained in Example 1A but havingimproved brilliance thereover.

1 claim:

1. ln a process for bright plating of zinc or cadmium from aqueousalkaline cyanide electroplating baths, the improvement which comprisesadding to said baths an aqueous composition containing, in parts byweight:

Sodium lignin sulfonate 1.1-4.8 Veratraldehyde 1.0

Vanillin 0.1-2.5 Corn syrup or glucose 1.7-5.0

Sodium lignin sulfonate 1.1-4.8 Verznruldehyde 1.0 Vanillin 0.1-2.5 Cornsyrup or glucose 1.7-5.0 Ammonium hepiamolyhdatc 0.02-0.4

and a molar equivalent amount of sodium bisulfite equal to the totalmolar equivalent amount of the vanillin and veratraldehyde.

3. In a process for still bright plating of zinc from aqueous alkalinecyanide electroplating baths, the improvement which comprises adding tosaid baths an aqueous composition containing, inparts by weight:

Sodium lignin sulfonate 1.1-4.8 Verutraldehyde 1.0 Vanillin 0.1-2.5 Cornsyrup or glucose 1.7-5.0 Ammonium heplamolybdate 0 017-02 and a molarequivalent amount of sodium bisulfite equal to the total molarequivalent amount of the vanillin and veratraldehyde.

4. A process according to claim 1 wherein the bath additive compositioncontains, in parts by weight:

Sodium lignin sulfonute 1.5-3.5 Verntrnldehyde 1.0

Vanillin 0.2-1.5 Corn syrup or glucose 2.2-4.5

and a molar equivalent amount of sodium bisulfite equal to the totalmolar equivalent amount of the vanillin and veratraldehyde.

5. A process according to claim 2 wherein the bath additive compositioncontains, in parts by weight:

Sodium lignin sulfonate 1.5-3.5 Veratraldehyde 1.0 Vanillin 0.2-1.5 Cornsyrup or glucose 1.2-4.5 Ammonium heptamolyhdate 005-0.}

and a molar equivalent amount of sodium bisulfite equal to the totalmolar equivalent amount of the vanillin and veratraldehyde.

6. A process according to claim 3 wherein the bath additive compositioncontains, in parts by weight:

Sodium lignin sulfonate 1.5-3.5 Veratraldehyde 1.0 Vanillin 0.2-1.5 Cornsyrup or glucose 2.2-4.0 Ammonium heptamolybdate 002-02 and a molarequivalent amount of sodium bisulfite equal to the total molarequivalent amount of the vanillin and veratraldehyde.

7. An electroplating brightener composition for addition to zinc orcadmium alkaline cyanide electroplating baths comprising an aqueoussolution containing, in parts by weight:

Sodium lignin sulfonate 1.1-4.8 Veratraldehyde 1.0

Vanillin 0.1-2.5 Corn syrup or glucose 1.7-5.0

and a molar equivalent amount of sodium bisulfite equal to the totalmolar equivalent amount of the vanillin and veratraldehyde.

8. An electroplating brightener composition for addition to cadmiumbarrel or still plating or zinc barrel plating alkaline cyanideelectroplating baths comprising an aqueous solution containing, in partsby weight:

Sodium lignin sulfonate 1.1-4.8 Verutraldehyde 1.0 Vanillin Gal-2.. Cornsyrup or glucose 1.7-5.0 Ammonium heptamolyhdate 0.( -0.4

and a molar equivalent amount of sodium bisulfite equal to the totalmolar equivalent amount of the vanillin and veratraldehyde.

9. An electroplating brightener composition for addition to zinc stillplating alkaline cyanide electroplating baths comprising an aqueoussolution containing, in parts by weight:

Sodium lignin sulfonate 1.1-4.8 Veratraldehyde 1.0 Vunillin 0.1-2.5 Cornsyrup or glucose 1.7-5.0 Ammonium heptamolybdate 0017-02 and a molarequivalent amount of sodium bisulfite equal to the total molarequivalent amount of thevanillin and veratraldehyde.

10. A composition according to claim 7 containing, in parts by weight:

Sodium lignin sulfonate 1.5 Veratraldehyde 1.0

-Continued Vanillin 0.2-1.5 Corn syrup or glucose 2.2-4.5

Sodium lignin sulfonate l -35 Verutraldehyde L0 Vanillin 0.2-],5 Cornsyrup or glucose 2.2-4.5 Ammonium heptumolybdate 005-03 and a molarequivalent amount of sodium bisulfite equal to the total molarequivalent amount of the vanillin and veratraldehyde.

12. A composition according to claim 9 containing. in parts by weight:

Sodium lignin sulfonate l.53.5 Vcratruldehyde L0 Vanillin 0.2-].5

Corn syrup or glucose 2.2-4.0 Ammonium heptamolybdate 002-01 and a molarequivalent amount of sodium bisulfite equal to the total molarequivalent amount of the'vanillin and veratraldehyde.

1. In a process for bright plating of zinc or cadmium from aqueousalkaline cyanide electroplating baths, the improvement which comprisesadding to said baths an aqueous composition containing, in parts byweight:
 2. In a process for barrel or still bright plating of cadmium orbarrel plating of zinc from aqueous alkaline cyanide electroplatingbaths, the improvement which comprises adding to said baths an aqueouscomposition containing, in parts by weight:
 3. In a process for stillbright plating of zinc from aqueous alkaline cyanide electroplatingbaths, the improvement which comprises adding to said baths an aqueouscomposition containing, in parts by weight:
 4. A process according toclaim 1 wherein the bath additive composition contains, in parts byweight:
 5. A process according to claim 2 wherein the bath additivecomposition contains, in parts by weight:
 6. A process according toclaim 3 wherein the bath additive composition contains, in parts byweight:
 7. AN ELECTROPLATING BRIGHTENER COMPOSITION FOR ADDITION TO ZINCOR CADMIUM ALKALINE CYANIDE ELECTROPLATING BATHS COMPRISING AN AQUEOUSSOLUTION CONTAINING, IN PARTS BY WEIGHT:
 8. An electroplating brightenercomposition for addition to cadmium barrel or still plating or zincbarrel plating alkaline cyanide electroplating baths comprising anaqueous solution containing, in parts by weight:
 9. AN ELECTROPLATINGBRIGHTENER COMPOSITION FOR ADDITION TO ZINC STILL PLATING ALKALINECYANIDE ELECTROPLATING BATHS COMPRISING AN AQUEOUS SOLUTION CONTAINING,IN PARTS BY WEIGHT:
 10. A composition according to claim 7 containing,in parts by weight:
 11. A composition according to claim 8 containing,in parts by weight:
 12. A composition according to claim 9 containing,in parts by weight: